The critical fluctuations in a mesoscopic superconducting ring are studied within the Ginzburg-Landau approach. The nonlocal conductivity as well as the specific heat are calculated as functions of the magnetic flux $\Phi$ through the ring. At $\Phi ={\Phi }_0/2$ two low-energy eigenstates become degenerate and near this point the behavior of fluctuation-dependent quantities changes dramatically: both the zero Fourier component ${\sigma }_0$ of the fluctuation conductivity and the specific heat become nonmonotonic functions of $|\Phi -{\Phi }_0/2|$ with rather special resonant structure.

• Received 6 April 2011

DOI:https://doi.org/10.1103/PhysRevB.84.064527